Cons
Adapter would not enable after install. Only USB 2.0, not 3.0. Setup software kept prompting for file install confirmation.

Bottom Line

Buffalo's AirStation AC866 IEEE 802.11ac USB-Wi-Fi Adapter provides good performance when paired with the company's latest 802.11ac router, though not the fastest 802.11ac performance we've tested. The adapter also sustains throughput at farther distances from the Buffalo router well, but there appear to be software issues with the setup.

Buffalo's AirStation AC866 IEEE 802.11ac USB-Wi-Fi Adapter ($49, street) is the company's companion adapter to its latest AirStation AC1750 Gigabit Simultaneous Dual Band Wireless Router. The AC866 adapter is a fairly standard stick, as far as USB wireless adapters go, though its setup process surprised me with some puzzling behavior. While the AC866 offers good performance with Buffalo's 11ac routers, I can't help but wonder how much better performance would be if this was a 3x3 adapter that supported USB 3.0.

SpecificationsThe AC866 is a dual-band adapter, capable of up to a theoretical 300 Mbps at the 2.4GHz band and up to 866Mbps at the 5 GHz band. It's a 2x2 adapter supporting double spatial streams, whereas the router is a more-powerful 3x3, triple-stream device that can support up to 1300 Mbps on the 5GHz band and 450Mbps at 2.4 GHz. The AC866 is not quite the ultimate wireless adapter for the AirStation AC1750, but pairing it with this router provides decent performance and range.

The device is a bit thicker than most USB sticks, measuring 0.59 by 1.22 by 3.66 inches (HWD) and weighing just over an ounce.

Only USB 2.0 is supported. I've seen the best wireless adapter performance from adapters that can connect to USB 3.0 ports. The slower speed of USB 2.0 seems to hinder throughput rates a bit when compared to USB 3.0 wireless adapters.

Installing the AC866The setup utility on the disc, gives the option of installing or not installing an available wireless client manager along with the drivers. This is a big plus for me—I have tested wireless adapters that force you to install the vendor's proprietary wireless utility. I find wireless managers that take over wireless networking settings in Windows can cause issues with the adapters and connecting to wireless networks. I prefer simply letting Windows handle Wi-Fi connection.

While I was glad I wasn't forced to use Buffalo's wireless client manager, the setup process was not without some hassle: During setup I kept receiving a pop-up alert asking me to confirm if I really wanted to install a file as files were being loaded to install the drivers. It was a fairly lengthy installation process, so there were quite a few files to confirm. And I kept getting asked to confirm individual files to install, even after checking off the setting "Always trust software from Buffalo."

The problem is not necessarily with Buffalo's software. It could very well be a Windows issue, though I routinely install wireless adapters on this particular Windows PC and have never had to constantly confirm files to install.

This was not the only odd behavior I observed while installing the AC866. Once installation completed, the adapter was placed and remained in a disabled state when I viewed it in Windows network settings. Now, I had disabled the on-board wireless adapter as I do whenever installing a USB adapter. A right- click on the Buffalo adapter icon refused to place the adapter in an enabled state. I was only able to enable the device after reseating it my laptop's USB port.

Compared with Linksys's Wireless Mini USB Adapter AC 580 (AE6000), the AC866 was on par performance-wise in 802.11ac mode, but it did even better than the Linksys unit at 5 GHz 802.11n mode.

The Buffalo adapter fared better in every wireless mode compared with several other USB adapters I've tested, including the Trendnet AC1200 Dual Band Wireless USB Adapter . Still, when it comes to 802.11ac performance, the best I've tested in PCMag's lab so far remains Edimax's AC1200 Wireless Dual-Band USB Adapter. Click on the image for performance comparisons with other wireless adapters we've tested.

Buffalo Slightly Ahead of HerdBuffalo's AC866 adapter performs well when paired with the company's latest 802.11ac router, though this combination doesn't provide the fastest 802.11ac performance we've tested. The adapter also sustains throughput at a farther distance away from the Buffalo router well. But the annoying requests for confirmation of file installations during setup and the fact that the adapter would not enable after software installation knocked down the unit's score. The Buffalo AirStation AC866 IEEE 802.11ac USB-Wi-Fi Adapter earns a solid three and half out of five stars for USB wireless adapters; the Edimax adapter remains our Editors' Choice.

Samara Lynn has nearly twenty years experience in Information Technology; most recently as IT Director at a major New York City healthcare facility. She has a Bachelor's degree from Brooklyn College, several technology certifications, and...

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